Add: Documentation and examples to @mavenomics/ui package

[quigleyj97]

This adds some much-needed docs and examples to the UI package, as well as a fancy little integration tester named Storybook.

The minor changes are;

• making listbox CSS rules use the style variables
• documenting which rules are used by which components

Added some docs to the ListBox, TreeView, and TreeModel, including examples.

Added Storybook, and a "story" for the ListBox.

You can run the Storybook examples with yarn workspace @mavenomics/ui run storybook, which will compile and run them in a new browser tab. It's actually pretty slick, with watchers and hot module reload:

In the future I plan on adding similar examples for the TreeView and TreeList. This will make future iteration on the components much easier (since they no longer need to run in the main app and will cycle much faster), as well as generate a useful, low-maintenance doc artifact.

[quigleyj-mavenomics]

Reverted this since the addition of Storybook seems to introduce a very puzzling error in Webpack for an unrelated package:

$ yarn workspace @mavenomics/chart-parts run webpack --watch --mode=development
yarn workspace v1.17.3
yarn run v1.17.3
$ C:\Source\MavenWorks\node_modules\.bin\webpack --watch --mode=development
C:\Source\MavenWorks\node_modules\webpack-cli\bin\cli.js:93
                                throw err;
                                ^

Error: Cannot find module 'core-js/modules/es6.regexp.split'

I'm not sure why chart-parts is so affected. Other bundlers work just fine...